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POc strcat with pointer
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copied!<p>I'm trying to use pointers and strcat from C. This is part of my learning process.</p> <p>The idea is the user inputs a string that contains digits and the output should return only the digits. So, if the user inputs <code>te12abc</code> the output should be <code>12</code>.</p> <p>This is my first try:</p> <pre><code>#include <stdio.h> #include <stdlib.h> #include <string.h> #include <ctype.h> #define SIZE 10 int main() { char palavra[SIZE]; char palavra2[SIZE]; char *pont = palavra; char *pont2 = palavra2; printf("Insert the string\n"); scanf("%s", palavra); do{ if (isdigit(*pont)){ strcat(palavra2, *pont); } *pont++; }while (*pont != '\0'); printf("\nThe number is:\n%s\n", palavra2); return 0; } </code></pre> <p>I believe that the pointer is working as expected but can't understand why strcat is not working.</p> <p>Made a second try that is the program finds a number, stores that char in one variable and only then try to use strcat with that variable. Here is the code:</p> <pre><code>int main() { char palavra[SIZE]; char palavra2[SIZE]; char temp; char *pont = palavra; char * pont2 = &temp; printf("Insert the string\n"); scanf("%s", palavra); do{ if (isdigit(*pont)){ temp = *pont; strcat(palavra2, pont2); } *pont++; }while (*pont != '\0'); printf("\nThe number is:\n%s\n", palavra2); return 0; } </code></pre> <p>Once again it gives me problems at strcat.</p> <p>Made one last attempt but without pointer and still strcat does not work. Here is the code:</p> <pre><code>int main() { int i = 0; char palavra[SIZE]; char palavra2[SIZE]; char temp; printf("Insert the string\n"); scanf("%s", palavra); do{ if (isdigit(palavra[i])){ temp = palavra[i]; strcat(palavra2, palavra[i]); } i++; }while (palavra[i] != '\0'); printf("\nThe number is:\n%s\n", palavra2); return 0; } </code></pre> <p>Can you point me to the right direction? Don't now what more can I do..</p> <p>Regards,</p> <p>favolas</p>

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